Electric lamp



April. 16, 1935. A. A. THOMAS ELECTRIC LAMP Filed Aug. 20, 1932 INVENTOR Patented Apr. 16, 1935 1,997,781

UNITED STATES PATENT OFFICE ELECTRIC LAMP Adolph A. Thomas, New York, N. Y. Application August 20, 1932, Serial No. 629,598

2 Claims. (Cl. 176122) My invention relates to electric lamps, and its small pieces of asbestos or the like strung on 9. object is to provide a novel form of housing for wire 2| and placed over the inner bulb before the electric elements of certain kinds of lamps. the outer bulb is placed over it. The bulbs Ill and There is, for example, a type 01' electric vapor ll are exhausted of air through tips 22 and 23 lamp which requires high temperature inside for or otherwise, and the inner bulb is in some cases 5 eflicient operation. To maintain this high temfilled with gas or vapor before the tip 22 is sealed perature in the lamp regardless of weather condioil, or is otherwise properly treated. tions, I provide the glass tube or bulb containing Th double-Walled l unit i moun the electrodes with a transparent heat-insulating on a su ta e as member which is c m nt d l0 jacket which forms a permanent structural part to the extension l3 and carries Contact p 5 of the lamp. This jacketisformed by mountinga connected to the electrodes in bulb III. In the second glass bulb in spaced relation over the inner b i aspect f my i v i n, h p cific construcbulb of the lamp, these bulbs being integrally tion and arrangement of the electrodes in bulb united in a fused joint, The annular space be- ID are immaterial. By way of example, I have tween the two nested bulbs may be evacuated or Sho a cathode filementgzli and a P 0f anodes l6 otherwise rendered heat-insulating, In ome in- 21-28 between which the cathode is arranged. stances the jacket space around the inner bulb These electrodes are mounted on four rods or may contain a light-modifying medium or a 0001- still? wires 29 embedded in and passin through ing medium, the latter being preferably kept in t P ss and Wires Connect the S pp circulation. The outer bulb also acts as a me- 8 rods 19 t0 the Contact P ny Other 20 chanical shield for the inner bulb, practical mounting and electric connections for A practical form of my invention is shown in electrodes y be usedthe accompanying drawing, inwhich Describing briefly the operation of the par- Fig. 1 is a longitudinal section through my new 1716111111 amp illustrated in I a l ass 25 electric lamp, the base being indicat i d tt that the inner bulb l0 contains a small amount 25 outline; of metallic sodium, which evaporates at high heat Fig. 2 shows the three glass arts of the lam to form a glowing vapor. When the filament 26 separated to illustrate the method of assembly; isbrought to incandescence by an electric current, and and when a proper voltage is applied to the anodes Fig. 3 shows a modified construction in which are discharge is Started a d t e result- 30 the space between the two nested b'ulbs of the s hi h te p ature in the bu b a s the lamp is kept filled withacooling medium in circul i sodium 1 a v p w i h ive Out 8- lation. brilliant yellow light. To maintain sufilcient The inner bulb or cylinder ill of glass is formed 1 0 pressure Within bulb it must be p with an integral annular flange l2 near the base, at a hi h temperatu e-say, betw 200 and 35 and the bulb terminates in an extension ii to 300 C. for sodium vapor lamps- Thi high whlch the press I4 is sealed in the usual way. P ur i maintained i b y ea o t The bulb III with its parts I! and I3 is preferably vacuum jacket l8, which prevents (or at least blown in a mold, and the press It is inserted reduces to a minimum) the dissipation of heat 4 through the opening ill to the edge of which is g erated Within he bulb 0 during the opere- 40 fused the edge l6 of the press. tion of the lamp.

The outwardly projecting flange or shoulder l2 In some instances, the outer bulb l8 may be is for the purpose of supporting an outer glass used merely as a mechanical shield for the inner bulb or cylinder l'l adapted to fit over the inner bulb l0. d in that case there d b 0 exbulb and forming therewith an annular space l8. haustion oi space [8. This space may also be 45 The edge IQ of glass cylinder I1 is fused to the filled with q d G for modifying the light projecting flange l2 of the inner bulb l0, whereemitted by bulb ill. For example, if the light by the two bulb are integrally and permanently coming from bulb I0 is of a certain color which is united in concentrically spaced relation. The undesirable in a specific case, that color can be annular chamber l8 between the two bulbs may be modified or changed by filling the surrounding 50 evacuated to the required degree or otherwise space I8 with a liquid or gas adapted to alter the I treated to form a heat-insulating jacket for the color of the original light. inner bulb. If desired, shock-absorbing pads'tll For another use of my double-walled bulb, I may be inserted between the bulbs to strengthen may fill the jacket space l8 with a heat-absorbthis double-walled unit. The pads 20' may be ing medium to keep the lamp cool, or to prevent 55 its temperature from rising too high. Such-an arrangement would be necessary for high-power tubes in radio systems, where separate water jackets have been heretofore used. In Fig. 3 the outer bulb or cylinder II has a pair of open nipples 8| and 32 connected to pipes at and 34, respectively. These pipes are in a circulatory system adapted to pass a suitable cooling medium through the jacket space II. this medium preferably entering through the lower nipple SI and passing out through the upper nipple 32. Clear water may be used for this purpose, or a transparent gas that has been previously cooled.

In one of the claims I refer to flange I! as a hollow bead. When the inner bulb Ill comes out of the mold where it is blown, this bead is hollow, as shown in Fig. 2. However, it is possible that in fusing the rim IQ of the outer bulb II to the projecting flange l2, some of the melting glass may partly fill in the hollow space of the bead. I do not exclude this possibility when I refer to the bead H as hollow.

Although I have herein set forth certain speciflc constructions to describe my invention, I want it understood that I do not restrict myself to any details unless specified in the appended claims which define the scope of my invention.

I claim as my invention:

1. An electric vapor lamp comprising an integral double-walled unit of glass which consists of an inner bulb and an outer bulb spaced therefrom, the inner bulb having a projecting annular flange to which the rim of the outer bulb is fused, the sealed space between said bulbs having heatinsulating properties, a glass press closing one end of the inner bulb and forming a permanent integral part thereof, four insulated conducting rodsorstiifwiresmountedinsaidpressandextending into the inner bulb, a heating element in the inner bulb connected to one pair of said rods, two glow electrodes in the inner bulb connected tothe otherpairofrods,allofsaidrodsbeingout of engagement with the outer bulb, a base on which said unit is mounted. and four insulated contact pins projecting from said base and electrically connected to said four conductor rods.

2. A heat-insulated electric vapor lamp comprising a single-walled inner bulb of glass permanently sealed and having an integral hollow bead formed between its ends, said bead constituting an outwardly projecting annular flange, an outer glass bulb placed over the inner bulb in spaced relation thereto, the circular rim of said outer bulb engaging said annular flange and being fused thereto, whereby said bulbs form an integral unit of glass which is double-walled from its outer end to said flange, the single wall of said inner bulb extending beyond said double-walled portion of the unit and constituting the base end of said unit, a glass press sealed to said singlewalled base end, electrodes supported by said press and extending into said inner bulb in operative relation, said electrodes comprising a cathode and at least one anode, the sealed inner 

